Coherent Scattering of Near-Resonant Light by a Dense, Microscopic Cloud of Cold Two-Level Atoms: Experiment versus Theory

Stephan Jennewein (1) , Ludovic Brossard (1) , Yvan R. P. Sortais (1) , Antoine Browaeys (1) , Patrick Cheinet (2) , Jacques Robert (2) , Pierre Pillet (2)

1 Laboratoire Charles Fabry / Optique Quantique
2 LAC - Laboratoire Aimé Cotton

We measure the coherent scattering of low-intensity, near-resonant light by a cloud of laser-cooled two-level rubidium atoms with a size comparable to the wavelength of light. We isolate a two-level atomic structure by applying a 300 G magnetic field. We measure both the temporal and the steady-state coherent optical response of the cloud for various detunings of the laser and for atom numbers ranging from 5 to 100. We compare our results to a microscopic coupled-dipole model and to a multi-mode, paraxial Maxwell-Bloch model. In the low-intensity regime, both models are in excellent agreement, thus validating the Maxwell-Bloch model. Comparing to the data, the models are found in very good agreement for relatively low densities (n/k 3 0.1), while significant deviations start to occur at higher density. This disagreement indicates that light scattering in dense, cold atomic ensembles is still not quantitatively understood, even in pristine experimental conditions.

Domaines: Physique Quantique [quant-ph]; Physique Atomique [physics.atom-ph]

Stephan Jennewein, Ludovic Brossard, Yvan R. P. Sortais, Antoine Browaeys, Patrick Cheinet, et al.. Coherent Scattering of Near-Resonant Light by a Dense, Microscopic Cloud of Cold Two-Level Atoms: Experiment versus Theory. Physical Review A, 2018, 97, pp.053816. ⟨10.1103/PhysRevA.97.053816⟩. ⟨hal-02407782⟩